Extensible laminate materials that include films, especially elastic films, are commonly used for a wide variety of applications. For example, disposable absorbent articles typically include one or more components that rely on the elastic properties provided by an elastomeric laminate to provide a comfortable, conforming fit when the article is worn by a wearer. While elastic films are known to provide desirable elastic behavior in certain absorbent article components (e.g., side panels, waist bands, leg bands), the films may not provide a desirable tactile sensation (e.g., softness or smoothness) on the skin of a wearer of the article. Thus, the elastic film is typically joined to another material, which is intended to remain in contact with the skin of the wearer and provide the desired tactile sensation. For example, it is not uncommon for an elastic film layer to be sandwiched between two plastically extensible nonwoven layers, which are selected to provide a desired feeling of softness.
In some instances, for example when an elastic laminate is desired, a laminate may be subjected to an incremental stretching process, sometimes referred to as activation. The incremental stretching process permanently, mechanically deforms the plastically extensible nonwoven material of the laminate, which reduces the tendency of the nonwoven to resist stretching. But the film layer still exhibits desirable elastic behavior. One drawback to conventional incremental stretching processes and other rigorous manufacturing processes (e.g., embossing, high pressure bonding, thermal bonding) is the undesirable formation of holes, tears, or other discontinuities in the elastic film layer of the laminate. Additionally, conventional elastic film material may form holes or tears when subjected to the normal wear and tear of an article during use (e.g., contact with sharp objects, pulling and stretching by a wearer, rigorous activity of a wearer, and/or repetitive mechanical stress experienced during wear). Initially, a tear may start out small and be relatively inconsequential with regard to the desired function of the film, laminate, article component, and/or article, but as the size of the tear grows (e.g., due to the mechanical rigors typically associated with the use of the laminate and/or during the manufacturing process), the likelihood of catastrophic failure of the film, laminate, article component, or article increases. Unintended catastrophic failure of an article or component is almost always undesirable, but when the article is a disposable absorbent article such as a diaper or training pant, the consequences of catastrophic failure of the article or component may be especially acute. For example, the contents of the diaper or pant may escape from the article and/or the article may even become separated from the wearer.
In certain applications, it may be desirable to provide a laminate comprising a film that has pre-formed discontinuities (e.g., one or more apertures that extend at least partially through the thickness of the film and/or laminate) in order to control, for example, the breathability, permeability to liquids and/or solids, opacity, extensibility, etc. of the laminate. But openings in the film and/or laminate, whether desired or undesired, may grow and ultimately lead to partial or complete failure of the film and/or laminate to function as intended. Further, at least some manufacturers desire thinner/lower basis weight films to reduce material costs related to incorporating such films into laminates and/or articles. The potential problems associated with the formation of tears, holes, and apertures in a film may be even more acute in thinner/lower basis weight films.
In order to reduce the possibility that the elastic film in an extensible laminate will fail due to the presence of a hole, tear, and/or aperture, it may be desirable to increase the strength of the film. However, increasing the strength of the film typically means increasing the thickness of the film or forming the film from different materials, both of which may undesirably impact the cost and/or complexity of manufacturing the laminate and/or the suitability of the laminate for a particular use. For example, using a stronger film in a laminate intended for use in a side panel of a disposable diaper may increase the pressure applied by the side panel to the skin of a wearer, potentially causing undesirable red-marking and/or discomfort to the wearer. Additionally, increasing the overall strength of the film may only improve the film and/or laminate's resistance to the initial formation of a hole or tear and not its subsequent growth.
Another method for reducing the possibility of undesired growth of a tear, hole, and/or aperture in a film, especially in a low basis weight film, includes joining one or more reinforcing layers to the film. For example, the film may be formed with one or more commonly known “skin layers” (e.g., through a co-extrusion process). However, adding skin layers to improve the performance of the film and/or laminate comprising the film may undesirably increase the cost and/or complexity of producing the laminate and/or make the laminate unsuitable for its intended purpose. Thus, there remains a need to provide an extensible laminate including an elastic film that exhibits resistance to the growth of tears, holes, and/or apertures in a variety of circumstances (e.g., at a low basis weight) without the use of additional reinforcing materials.
Accordingly, it would be desirable to provide an extensible laminate that includes an elastic film which exhibits improved resistance to the propagation of a tear, hole, or aperture.